I have a 1958 F100 that we are dropping a 1985 300 straight 6 in. Does anyone know if a 1984 4 speed Mustang transmission will bolt up to it?

Thank you

 

That depends on what the Mustang transmission was behind. If it came out of a 5.0L car, then yes, it will bolt up to the 300. The 240 and 300 six cylinders share the bellhousing bolt pattern with the small block V8's. Watch out on the flywheel, though. Those big sixes were internally balanced and had a neutral balance flywheel. The V8's were all externally balanced and while their flywheels will physically bolt on to the big sixes, they will cause them to vibrate horribly and likely damage the engine. You have to run a 240 or 300 flywheel. If the transmission came out of a 4 or 6 cyl. Mustang, it might still be possible to change the bellhousing and get it to fit the big six, but I wouldn't advise it. The 4 and 6 cylinder cars often had lighter duty transmissions and the 300's torque will twist it apart the first time you get a little throttle-happy with it.

 

By '84, the Mustang 5.0 used the T-5 five speed transmission exclusively as their manual transmission. So if your 4 speed is from an 84, it would be from a 4 cylinder car, and I wouldn't recommend it for your application.

 

I suspect that is a 4-sp version of a non-World Class T-5 tranny, not a particularly desirable tranny.

 

We called the place where we got the tranny, and it came out of a V8. Thank you all for your help

 

Does the tranny use an external shifter, like the old Hurst style? or is it like a T5, integral rail shifter? Are you sure it's a 4-sp? I checked on the web, in '84 Mustang GT's used T5's. In fact I'm not seeing any 4-sp's used at all.

 

It is a Ford toploader 4sp

 

Just make sure it's not one of these...

Toploader Imposters


But if it is a "real" toploader, this chart will help you identlfy it's real beginnings.

http://www.davidkeetoploaders.com/tailhousingid.htm

 

I have an SROD from an early 80's fox. Not worth using: weak, all aluminum, and still a 1:1 4th gear. Plus I don't think a Mustang trans will put the shifter near the right location.